We have used immersion water heaters to show convection. You can usually
mount them inside a small aquarium full of water. If you then illuminate
the tank of water from the front, you can project a very clear image of the
convective currents on a wall behind the tank. We've generally used a fairly
bright LED, but most directed light sources can work. You can usually see
the hot water rising within seconds of turning on the immersion heater.

Similarly, you can use a waterproof peltier device; if you mount it
vertically, you can get hot water rising from one side, and cold water
sinking from the other.

Kenn

On Thu, Feb 17, 2011 at 2:27 PM, Rueckner, Wolf wrote:

> use Rheoscopic Fluid for flow visualization Great stuff!! available from
> www.novostar.com --- Wolfgang
>
>
>
> On Feb 17, 2011, at 4:22 PM, Anthony Lapinski wrote:
>
> > I am looking for an easy way to show convection in water. In the past I
> > put a beaker of water halfway on a hot plate. Turn it on and maybe 10
> > minutes later add a drop of food coloring. This is hit or miss depending
> > on the amount of water, when the heat is turned on, etc. Plus the drops
> > sinks slowly.
> >
> > Was thinking about using "heavy" particles that are insoluble in water
> > (e.g., sulfur, flour, etc.) and just heat the entire beaker. Does anyone
> > have good ideas for this?
> >
>
>
>

We have used immersion water heaters to show convection.=A0 You can usually=
mount them inside a small aquarium full of water.=A0 If you then illuminat=
e the tank of water from the front, you can project a very clear image of t=
he convective currents on a wall behind the tank. We've generally used =
a fairly bright LED, but most directed light sources can work.=A0 You can u=
sually see the hot water rising within seconds of turning on the immersion =
heater.

Similarly, you can use a waterproof peltier device; if you mount it ver=
tically, you can get hot water rising from one side, and cold water sinking=
from the other.KennOn T=
hu, Feb 17, 2011 at 2:27 PM, Rueckner, Wolf wrote:

> I am looking for an easy way to show convection in water. In the past =
I
> put a beaker of water halfway on a hot plate. Turn it on and maybe 10<=
br>
> minutes later add a drop of food coloring. This is hit or miss dependi=
ng
> on the amount of water, when the heat is turned on, etc. Plus the drop=
s
> sinks slowly.
>
> Was thinking about using "heavy" particles that are insolubl=
e in water
> (e.g., sulfur, flour, etc.) and just heat the entire beaker. Does anyo=
ne
> have good ideas for this?
>